The gram-positive bacterium Listeria monocytogenes is a bacterial pathogen which is known as the causative organism in several food-related outbreaks, illnesses and deaths. Listeriosis is a life-threatening infection of humans worldwide which is caused by Listeria monocytogenes and which is characterized by a variety of symptoms and conditions, including diarrhea, abortion and encephalitis. In industrialized countries, high mortality is associated with listeriosis following Listeria monocytogenes food contamination. In humans, the prevalence of listeriosis has risen significantly since the 1980s, resulting in intensified surveillance of Listeria monocytogenes in food industry. This contributed to a decrease of human listeriosis cases in the last two decades (McLauchlin 1987, Oevermann et al. 2008). However, its prevalence has again increased in the last few years (Gillespie et al. 2006, Goulet et al. 2008, Gillespie et al. 2009).
The species Listeria monocytogenes encompasses numerous strains and the genetic diversity amongst them is high (Doumith et al. 2004). Various strains have been implicated in both human and animal disease, and current surveillance schemes for foods are based on the assumption that all Listeria monocytogenes isolates are potentially pathogenic, resulting in costly recalls in food industry (Oevermann et al. 2010).
There is increasing public concern for food and water safety. The food safety and human diagnostics markets are in need of faster working, reliable, sensitive, specific, low cost bioassays and biosensors for Listeria bacterial detection.
Bacteriophages are viruses that infect bacteria. They are obligate intracellular parasites and lack their own metabolism. Phages are the natural enemies of bacteria. They are host-specific in that they infect specific bacterial species or even specific strains (Hagens and Loessner 2007). The extreme specificity of phages renders them ideal candidates for applications designed to increase food safety. Phages can be used for detection and monitoring of bacteria without interfering with the natural microflora.
It is an object of the present invention to provide bacteriophage-based means and methods for specifically and selectively identifying, detecting and/or monitoring Listeria. 